Vehicles are capable of performing various automated functions for user convenience. These automated functions are generally performed once a user is authenticated by said vehicles. One of such functions may be a passive entry feature that allow users to access a vehicle without using a key. Generally, in lieu of the key, a vehicle communicates with a mobile device (e.g., a smart phone or a key fob) to determine whether the mobile device is authenticated for use in passive entry, and based on the determination, the vehicle unlocks its doors. Conventional vehicles perform the authentication process once a vehicle door handle is actuated. Therefore, an inevitable delay is created between a time point in which a vehicle door is actuated to a subsequent time point in which the vehicle door is unlocked. Therefore, there is a need to minimize the delay to improve user convenience.